Process for producing wrinkle resistant cellulosic textile materials by catalysis with hydrogen halide gas



United States Patent PROCESS FOR PRODUCING WRINKLE RESISTANT CELLULOSIC TEXTILE MATERIALS BY CATAL- YSIS WITH HYDROGEN HALIDE GA'S Robert M. Reinhardt, New Orleans, and Joseph S. Bruno, Chalmette, La., assignors to the United States of America as represented by the Secretary of Agriculture No Drawing. Continuationimpart of application Ser. No. 395,627, Sept. .10, 1964. This application Sept. 19, 1967, Ser. No. 668,973

Int. Cl. D06m 7/02 U.S.Cl. 8-116.3 1 Claim ABSTRACT OF THE DISCLOSURE Cotton cellulosic materials are impregnated with N- methylol type crosslinking agents, particularly dimethylol ethyl carbamate, dried to normal regain at about 60 C., and the reaction catalyzed with an anhydrous hydrogen halide gas at temperatures in the range of 28 to 65 C., for periods of time in the range of 0.5 to 60 minutes.

A non-exclusive, irrevocable, royalty-free license in the invention herein described throughout the world for all purposes of the United States Government, with the power to grant sublicenses for such purposes, is hereby granted to the Government of the United States of America.

This application is a continuation-in-part to application Ser. No. 395,627, filed Sept. 10, 1964, now abandoned.

This invention relates to treatments which impart wrinkle resistance to cellulosic textile materials. More particularly, it provides a process whereby cellulosic textile materials may be impregnated with N-methylol type crosslinking agents and then treated with gaseous hydrogen halide catalyst to yield products exhibiting improved re siliency, wrinkle resistance, wash-wear properties, and durable creases.

Crosslinking cellulosic textile materials with N-methylol type finishing agents to produce dimensional stability and wrinkle resistance is well known by those skilled in the art. However, industrial processes for accomplishing this are almost invariably those in which the textile material is impregnated with a solution or emulsion containing the crosslinking agent and an acidic or latent acidic catalyst compound, the textile dried, and then cured by baking at high temperature, that is, about 140160 C. Other crosslinking processes utilizing N-methylol finishing agents are those in which the cellulosic material is crosslinked in'the wet state by treatment with a solution of the N-methylol agent and acidic catalyst. To date, processes of this latter type have not achieved widespread industrial usage.

Each of these crosslinking processes has some disadvantages which make desirable the development of new processes to produce wrinkle resistant textile materials.

A process wherein cellulose acetate or saponified cellulose acetate is treated by impregnating the cellulosic derivative with a urea-formaldehyde adduct, drying, and then exposing to the atmosphere in equilibrium with 36% aqueous hydrochloric acid, has been disclosed by Dreyfus and Moncrieff in US. Patent 2,235,141. This treatment provides only a limited degree of improvement in resiliency when applied to cotton material and when agents other than urea-formaldehyde adducts are employed. The improvement does not yield fabrics with a sufiicient level of wrinkle resistance for practical utility in Wrinkle-resistant or wash-wear garments.

It is an object of the present invention to provide a new process for finishing cellulosic textile materials with N- methylol type crosslinking agents to produce improved Patented June 17, 1969 involve the use of inexpensive, conventional N-me'th'ylol type crosslinking agents and gaseous hydrogen halide cata lysts, relatively low temperatures, and not unduly long reaction (or curing) times. The process essentially consists" of the following steps: (1) impregnating the cellulosic textile material with a solution, preferably aqueous, containing an N-methylol type crosslinking agent, (2) drying, or evaporating the solvent, (3) treating the N-methQ V ylol crosslinking agent-containing cellulosic material with anhydrous hydrogen halide gas, such as hydrogen chloride, hydrogen bromide, and the like, to bring about reaction between the N-methylol agent and available cellulosichydroxylgroups, and (4) washing the treated material to remove unused reactant, catalyst, and byproducts.

In a preferred embodiment of the instant invention wherein cotton is the cellulosic material, dimethylol ethyl carbamate is the N-methylol type crosslinking agent, and anhydrous hydrogen chloride gas is the catalyst, the process comprises the following steps for improving the wrinkle resistance and resiliency of, and imparting durable creases and wash-wear properties to cotton:

(a) Padding the cotton material with an aqueous solution containing about from 7% to 15% by weight of dimethylol ethyl carbamate, an aminoplast creaseproofing and crosslinking agent,

(b) Drying the wet, impregnated cotton material from (a) at about 60 C. until the fibers of the said material contain about their normal moisture regain value,

(c) Exposing the dry, impregnated cotton material from (b) to at least 0.5%, based on the weight of the cotton material treated, of anhydrous hydrogen chloride gas catalyst, for periods of time about from 0.5 to 60 minutes, at temperatures about from 28 to 65 C., the longer periods of time being employed with the lower temperatures, to catalyze the crosslinking reaction between the crosslinking chemical agent and the cellulosic chains, and

(d) Removing the thus exposed cotton material from the hydrogen chloride gas atmosphere, neutralizing the residual catalyst and acidic by-products with a dilute aqueous alkaline solution, and water washing and drying the resulting chemically modified cellulosic cotton material to remove unused reactants, residual catalyst, and byproducts.

The reaction between N-methylol type finishing agents, which are used to impart wrinkle resistance, and cellulosic textile materials is believed to proceed by a mechanism in which the cellulose chains are crosslinked. The uncatalyzed reaction is so slow that practically no reaction takes place even upon reaction times of many months. With acidic catalysis, the reaction time can be shortened markedly. With a combination of acidic catalysis and elevated temperature, as in conventional pad-dry-cure finishing, re-

action times of a minute or two, or even less, are possi-" ble. From practical considerations, however, speed of re-' action must be balanced against strength loss due to acidic hydrolysis of the cellulosic chains. The present invention in which gaseous hydrogen halide catalysis is employed has the advantage that relatively low temperatures are opdimensional stability (shrink resistance), decreased tearing strength, reduced water absorption, reduced aflinity for di- 3 rect dyes, improved rot resistance, and insolubility in the usual cellulose solvents, such as cupraethylenediamine.

Products of the present invention, in general, exhibit the typical characteristics of crosslinked cellulose. However, the degree of change of some properties, as compared with the unmodified cellulosic starting material, is often significantly less than that of other crosslinking processes. For example, moisture regains of the products of the present invention are generally greater or only slightly lower than that of the uncrosslinked starting material. Products of other crosslinking processes generally have markedly lower moisture regain values.

The commercial importance of a textile product with the properties imparted by crosslinking is obvious to those skilled in the art of textile finishing. To obtain the property of wrinkle resistance, for example, in the United States alone, approximately two billion yards of cotton fabric were treated in 1961. A more satisfactory crosslinking process could affect further increases in this already large production figure.

In addition to wrinkle resistance and wash-wear properties, durable creases and pleats may be imparted to cellulosic textile materials by the process of this invention. Creases and pleats are introduced, as desired, in the N- methylol finishing agent-impregnated cellulosic material which is then treated with anhydrous hydrogen halide gas while in such configuration. The cellulose crosslinks produced by the reaction hold the textile in the creased configuration. The creases are durable to repeated laundering and wearing by the same mechanism which operates to make flat, smooth areas resistant to wrinkling and mussing.

As stated above, in the process of the present invention, cellulosic textile materials are impregnated with a solution of the N-methylol crosslinking agent, the solvent removed, and the N-methylol crosslinking agent-containing cellulosic material treated with anhydrous gaseous hydrogen halide to bring about chemical reaction between the cellulosic hydroxyl groups and the N-methylol crosslinking agent. Adjustment of the variables of the process determines the degree of reaction and properties of the finished textiles. Among the variables which affect the properties of the product are: nature of the cellulosic starting material, pretreatments, fabric structure, nature and concentration of N-methylol crosslinking agent employed, moisture content of the N-methylol agent-containing cellulosic material, nature and concentration of gaseous hydrogen halide catalyst employed, time of treatment, and temperature of treatment. The variables are interrelated such that products with almost any desired degree of reaction, within an extremely broad range, can be produced by the process of the invention.

Fiber, yarn, or fabric may be treated; preferred treatment is carried out on fabric. The fabric treated may be composed of cotton, regenerated cellulose fiber, or etherified cellulosic fiber, and the like. Among etherified cellulosic fibers which may be employed are cotton fibers chemically modified so as to hear an ether substituent selected from the group consisting of methyl, ethyl, carboxymethyl, carboxyethyl, alpha-methyl carboxymethyl, phosphonomethyl, aminoethyl, hydroxyethyl, hydroxypropyl, carbamoylethyl, and sulfoethyl to a degree of substitution (D.S.) of about from 0.01 to 0.25 ether radicals per anhydroglucose unit of the cellulose chain.

Fabrics composed of blends of any of these cellulosic fibers, and fabrics composed of blends of these fibers with other fibers also may be treated by the process of this invention. When cotton fabric is used as the starting material, the fabric may he treated with the fibers in the native state or in a prepared state, that is, the fabric may be scoured, kierboiled, desized, bleached, mercerized, or dyed, or may be subjected to any combination of these pretreatment operations. Furthermore, cellulosic fibers which previously have been subjected to any treatment stable to acid hydrolysis and which still have sites available for further reaction may be treated by the process of this invention.

Treatment of the cellulosic textile material with softeners, hand modifiers, and other additives prior to impregnation with the N-methylol crosslinking agent or inclusion of such additives with the N-methylol crosslinking agent in the impregnation bath is often beneficial. Pretreatment with emulsified polyethylene or application of polyethylene along with the N-methylol agent, for example, results in a finished fabric with higher tearing strength and higher wet and dry (conditioned) crease recovery angles than cotton fabric treated similarly but without application of polyethylene.

N-methylol crosslinking agents which may be used in carrying out the process of this invention include the N-methylol agents conventionally used for imparting wrinkle resistance to cellulosic fabrics. These agents are monomers or relatively low molecular weight polymers, such as dimers or trimers, resulting from the condensation of formaldehyde and suitable compounds bearing .amide groups or groups of amidic character. Thus applicable in this invention are the ureaformaldehyde resins, including the methylol ureas and alkyl ethers, particularly methyl ethers of methylol ureas, the cyclic ureas, as for example, ethyleneurea, dihydroxyethyleneurea, propyleneurea, their formaldehyde condensates and alkylated derivatives, and the like, and formaldehyde condensates of monoalkyl carbamates, aliphatic polycarboxylic amides, triazones, triazines, and the like, and their alkylated derivatives. These agents may be employed singly, or in combination with one another, or in combination with other resins the presence of which does not adversely affect the process of this invention.

The N-methylol crosslinking agent may be applied to the cellulosic textile material by any of the techniques conventionally employed in textile wet processing. That is, the textile material may be immersed in a solution of the N-methylol crosslinking agent, followed by passing through pad rolls or by centrifugation to remove excess solution, or may be impregnated by spraying with a solution of the agent. A wet pickup of the N-methylol crosslinking agent solution by the cellulosic material of about from 50% to (of the weight of the textile) is recommended. Concentration of the N-methylol crosslinking agent in the solution employed may be varied about from 1% to 50% (of the weight of the solution). The preferred range of concentration, however, includes about from 7% to 15%. N-methylol crosslinking agent solutions are most simply and economically prepared and used as aqueous solutions. Other solvents, however, may be employed, if desired.

After impregnation of the textile with the solution of N-methylol crosslinking agent, the water or other solvent used is removed by drying or evaporating. Moisture content of the impregnated cellulosic fibers at the time of the gaseous hydrogen halide treatment affects the rate and extent of reaction and thus the properties of the treated material. Best results are obtained when the fibers contain about their normal moisture regain value (about from 6% to 10% moisture). When the fibers contain less than normal regain, the rate and extent of reaction are decreased; when completely dry, little or no reaction occurs. With moisture contents above about 10%, the rate and extent of reaction decrease as the moisture content is increased.

Hydrogen halide gases which may be employed in this invention include hydrogen fluoride, hydrogen chloride, hydrogen bromide, and hydrogen iodide. Because of corrosion difficulties, cost, availability, and molecular weight considerations, hydrogen chloride and hydrogen bromide are preferred as gaseous catalysts and are employed as the anhydrous gases in the process of the present invention.

The concentration of hydrogen halide gas employed to catalyze the reaction may be varied from about 0.25%

OWF (percent by weight of catalyst based on weight of fabric treated) to about OWF. The preferred range of concentration includes about from 0.5% OWF to 10% OWF. In general, the higher the catalyst concentration employed, the fasterthe reaction of the N-methylol crosslinking agent with the cellulosic material and the shorter the treatment time necessary to achieve a given degree of wrinkle resistance.

The hydrogen halide treatment time necessary to carry out the process of this invention varies from a few seconds to about one hour. The treatment time employed in any given case is a function of the fabric properties desired and of the temperature of the treatment and of the concentration of catalyst used. In general, treatment time is adjusted inversely with temperature of treatment and catalyst concentration. Treatment times of about from 0.5 to 10 minutes are preferred, as they can be utilized to produce high degrees of wrinkle resistance in cotton fabrics with strength losses less than or equal to those sustained in presently conventional wrinkle resistance finishing processes.

The anhydrous gaseous hydrogen halide treatment is carried out at ambient atmospheric pressure.

A wide range of temperatures may be employed in carrying out the hydrogen halide treatment step of the process of this invention. Temperatures of about 25 C. to 80 C. can be used. It is generally preferable to conduct the hydrogen halide treatment at the lower temperatures, from about room temperature to about 65 C., because as the temperature of this treatment is increased, loss of strength of the product may become excessive if other variables of the process are not carefully adjusted to compensate for the higher treatment temperature.

After treatment, the textile product should be thorlished by Committee D-13 of the American Society for Testing Materials.

Moisture regain.-ASTM Test Method D629-59T was used for the determination of moisture regain.

The following examples are given to illustrate further the process of this invention.

EXAMPLE 1 Samples of the following: (i) 80 x 80 cotton printcloth which had been scoured, bleached, and desized; (ii) printcloth which had been carboxymethylated to a D.S. of 0.11 by treatment with sodium chloroacetate and sodium hydroxide by the process of patent application, Ser. No. 275,169, filed Apr. 23, 1963; (iii) printcloth which had been carboxyethylated to a D.S. of 0.07 by treatment with acrylamide and sodium hydroxide; (iv) printcloth which had been hydroxyethylated to a D.S. 0.11 by treatment with ethylene oxide and sodium hydroxide; (v) printcloth hydroxyethylated similarly to a D.S. of 0.15; and (vi) printcloth hydroxyethylated similarly to a D.S. of 0.21; were immersed in an aqueous solution containing 10% dimethylol ethyl carbamate, padded to about 85% wet pickup by passing through squeeze rolls, mounted on pin frames, and dried until the fibers of the said materials contained about their normal moisture regain value (60 C. for seven minutes). The samples were then placed in a glass reaction chamber and treated with 5%, based on the weight of the fabric treated (OWF), of anhydrous hydrogen chloride gas at 42 C. for five minutes, soaked briefly in 1% sodium carbonate solution, washed, and dried. In Table I are shown the crease recovery angles (both conditioned and wet), breaking strengths, and moisture regains, before and after the crosslinking treatment, and the nitrogen content of the treated samples.

TABLE I Untreated Treated Crease recovery Crease recovery angle (W+F) Moisture angle (W+F) Moisture M Brk. Str regain, M Brk. Str. regain Fabric treated C0nd., deg. Wet., deg. (W), 1b. percent percent; Cond.,deg. Wet, deg. (W), lb. percent Cotton 196 167 49. 7 6. 65 0. 68 261 263 29. 6 6.36 Carboxymethylated cotton, D.S. 0.11 183 180 49. 3 8.44 0. 34 237 220 41. 9 8. 58 Oarboxyethylated cotton, D.S. 0.07 181 204 48. 9 8.10 0. 46 249 276 35. 5 8. 58 Hydroxyethylated cotton, D.S. 0.11 190 190 48.8 6. 90 0. 54 281 281 30. 6 6. 73 Hydroxyethylated cotton, D.S. 0.15"--." 199 192 50. 6 7. 63 0. 55 297 307 31. 8 6. 85 Hydroxyethylated cotton, D.S. 0.21. 194 195 51. 3 7. 61 0. 307 302 31. 5 7. 32

oughly washed to remove unused reactant, residual cata- EXAMPLE 2 lyst, and byproducts. It is often desirable to first neutralize residual catalyst and acidic byproducts by immersing the treated textile material in a dilute solution containing sodium carbonate, sodium bicarbonate, sodium hydroxide, sodium phosphate, or the like.

Properties reported in the examples below were determined employing the following test procedures:

Crease recovery angles-Determinations of conditioned crease recovery angles (commonly called dry cease recovery angles) were carried out on samples equilibrated at 70 F., and 65% relative humidity by the test procedure of the American Association of Textile Chemists and Colorists, Tentative Test Method 661959T.'This procedure is described on pages B137-8 of the 1963 Technical Manual of the A.A.T.C.C. (volume 39).

Wet crease recovery angles were determined using this same procedure on samples which had been soaked for five minutes at 150 F. in water containing a nonionic wetting agent and blotted to remove excess water.

Appearance of creases-The appearance of creases before and after laundering was estimated by comparison with the standards of A.A.T.C.C. Tentative Test Method 88C-1962T, pages B93-4 of the 1963 Technical Manual of the A.A.T.C.C.

Breaking strength-This property was determined by the procedure of ASTM Test Method D1682-59T as given in ASTM Standards on Textile Materials pub- Samples of x 80 cotton printcloth which had been scoured, bleached, and desized were impregnated with 10% aqueous solutions of the following: (i) dimethylol ethyleneurea, (ii) dimethylol ethyl carbamate, (iii) dimethylol ethyl triazone, (iv) methylated trimethylol melamine, and (v) tris (N-methylol-Z-carbamoylethyl)amine. The fabric samples were immersed in a solution of the crosslinking agent, padded to about Wet pickup by passing through squeeze rolls, mounted on pin frames, dried at 60 C. for 7 minutes, then treated in a glass reaction chamber with 4% OWF of anhydrous gaseous hydrogen chloride at 40 C. for five minutes, neutralized with 1% sodium carbonate solution, washed, and dried. Properties of the treated samples are given in Table II.

TABLE II Crease recovery Angle (W-t-F) 00nd, Wet

7 EXAMPLE 3 Samples of 80 x 80 cotton printcloth (scoured, bleached, and desized) were impregnated with 10% aqueous solutions of the following: (i) dimethylol methyl carbamate, (ii) dimethylol ethyl carbamate, (iii) dimethylol ethyleneurea, and (iv) dimethylol propyleneurea. The fabric samples were immersed in a solution of the crosslinking agent, padded to about 85% wet pickup by passing TABLE IV Fabric impregnation Hydrogen chloride treatment Properties of treated fabrics Conditioned Crossliuking crease Agent, H01 Cone. recovery Break. Moisture Crosslinking Gone percent Tune, 'Iemp., angle strength regain, agent used 1 percent OWF min. deg. percent (W+F) deg. (W) 1b. percent 10 3 4 65 0 .56 257 36 .1 5 .4 0 .5 10 65 0 .60 252 35 .6 5 .3 10 0.5 60 65 0.71 267 27 .0 4 .6 10 10 0 .5 43 0 .59 242 38 .5 6 .0 10 10 1 43 0.68 250 34 .2 6 .4 7 4 7 .5 40 1 .01 259 .6 6 .3 10 4 5 40 1.31 264 .6 6 .8 13 2 2.5 1 .71 268 31 .3 7 .2 7.5 2 7 .5 40 0.43 258 35.0 6.5 7 .5 6 2.5 40 0.43 262 29.9 6.0 15 4 7 .5 40 0.90 258 31.9 6 .1 15 10 5 40 0 .93 252 26 .1 6 :3

1 DMEC=dimethylol ethyl carbamate; DMEU=din1ethylolethy1eneuree.

through squeeze rolls, mounted on pin frames, dried at 60 C. for seven minutes, then treated in a glass reaction chamber of 4% OWF of anhydrous gaseous hydrogen bromide at 42 C. for five minutes, neutralized with 1% sodium carbonate solution, washed and dried. Properties of the treated samples are given in Table III.

TABLE III Crease recovery Samples of 80 x 80 cotton printcloth which had been scoured, bleached, and desized were impregnated with various solution of dimethylol ethyl carbarnate or dimethylol ethyleneurea as shown in Table IV, padded to about 85% wet pickup by passing through squeeze rolls, mounted on pin frames, dried at 60 C. for seven minutes, and then treated in a glass reaction chamber with anhydrous gaseous hydrogen chloride under various treat ment conditions as detailed in Table IV. After treatment, samples were neutralized with 1% sodium carbonate solution, washed and dried. Properties of the treated samples also are given in the table.

EXAMPLE 5 A sample of 80 x 80 cotton printcloth which had been scoured, bleached, and desized was impregnated with an aqueous solution containing 10% dimethylol ethyl carbamate, padded to about 85% wet pickup by passing tumble dryings, the appearance of the crease was still given a rating of 5 on this scale. The appearance of the crease remained unchanged through these repeated launderings and dryings without the necessity of touch-up ironing.

We claim:

1. A process for improving the wrinkle resistance and resiliency of, and imparting durable creases and washwear properties to cotton, comprising the following steps:

(a) padding the cotton material with an aqueous solution containing about from 7% to 15% by weight of dimethylol ethyl carbamate, an aminoplast creaseproofing and crosslinking agent,

(b) drying the wet, impregnated cotton material from (a) at about 60 C. until the fibers of the said material contain about their normal moisture regain 'value,

(c) exposing the dry, impregnated cotton material from (b) to at least 0.5%, based on the weight of the cotton material treated, of anhydrous hydrogen chloride gas catalyst, for periods of time about from 0.5 to 60 minutes, at temperatures about from 28 to 65 C., the longer periods of time being employed with the lower temperatures, to catalyze the crosslinking reaction between the crosslinking chemical agent and the cellulosic chains, and

(d) removing the thus exposed cotton material from the hydrogen chloride gas atmosphere, neutralizing the residual catalyst and acidic byproducts with a dilute aqueous alkaline solution, and water washing and drying the resulting chemically modified cellulosic cotton material to remove unused reactants, residual catalyst, and byproducts.

References Cited UNITED STATES PATENTS 2,235,141 3/1941 Dreyfus et a1. 11762.2 XR 2,311,080 2/ 1943 Pinkney 8-1l6.4 3,219,632 11/1965 Frick et a1 8ll6.3

LEON D. ROSDOL, Primary Examiner.

I. D. WELSH, Assistant Examiner.

US. Cl. X.R. 8-129 

